1. Field of Art
This invention relates generally to electrical generators, and especially to a setback or inertia generator for projectile electrical fuzes.
2. Prior Art
An early setback generator is shown in U.S. Pat. NO. 3,120.187 issued to G. Wyser on Feb. 4, 1964. A more recent setback generator is shown in FIGS. 1 and 2. The generator consists of a relatively large, hollow cylindrical cast "Alnico-5" magnet 10, two magnetically soft end caps, one a washer 12, and the other a disk 14, a cylindrical core 16 which completes the magnetic circuit, and a coil 18 hich surrounds the core. Sufficient flux is generated by the permanent magnet 10 to completely saturate the core 16, and the core is held in place against the inside face of the end cap 14 by the force of magnetic attraction. Upon setback, the core 16 moves away from the end cap 14, and the magnetic field in the core collapses to almost zero. This collapsing field induces a current in the coil which charges a capacitor through a series diode. The energy stored in the capacitor is then used to power a fuze detonating circuit, as by an electrical timing circuit operating an electrical detonator. The energy that can be derived from such a generator is dependent on the magnitude of the field in the core and its rate of decay, and on the dynamic response of the inductance-resistance-capacitance circuit. For the prior art device described, core saturation at 15K gauss is a fundamental limitation. Higher storage energies can be achieved only by increasing the size of the core and the permanent magnet and by modifying the inductance and resistance parameter of the coil for optimum charging. An exemplory prior art device having an overall diameter of 1.5 inches and a length of 0.88 inches provided 225 .times. 10.sup.6 Erg output energy.